[gtk/wip/otte/macos-werror: 4/4] CI: turn on -Werror for MacOS build

[Benjamin Otte <otte src gnome org>]

commit 25074b946adfdc2cd613f7a56d5444dd3f4ff8c8
Author: Benjamin Otte <otte redhat com>
Date:   Wed Nov 3 23:35:03 2021 +0100

    CI: turn on -Werror for MacOS build
    
    The build is error-free and we want to keep it that way.
    
    We'd also like to make Timm do real work instead of having to fix clang
    warnings all the time and this build is a clang build.

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 212c857643..b7aab27c19 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -178,6 +178,7 @@ macos:
             -Dmedia-gstreamer=disabled
             -Dintrospection=disabled
             -Dcpp_std=c++11
+            -Dgtk:werror=true
             -Dpixman:tests=disabled
             _build
     - ninja -C _build